Characterization and Degradation of Ancient Architectural Red Sandstone in a Natural Erosion Environment

Round 1

Reviewer 1 Report (Previous Reviewer 3)

Monitoring historic buildings is a challenging issue everywhere and the requirement for accurate and trustworthy monitoring techniques is pressing. This way appropriate restoration, protection, or reinforcement tactics can be imagined based on the monitoring findings.

The current publication details a study on the characteristics and deterioration of historic architectural red sandstone exposed to natural erosion. In order to do this, a tiny piece of red sandstone was subjected to several experimental methods, including scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray computed tomography (X-CT). To determine the extent of the material's deterioration, the findings from the various procedures are examined independently, compared, and then correlated. There are four sections in the manuscript:  a good introduction presenting the challenges associated with historical buildings monitoring and a literature analysis of the current monitoring techniques, a Materials and methods section presenting the sample and the measuring techniques with adequate sketches, an Analysis of results section clearly presenting the main results and a conclusion.

This study is sound and interesting and may be of interest to the readers of the journal. Minor comments can be formulated:

-          Introduction: line space is not constant throughout the paragraphs

-          Table 4: table width should be reduced to follow the journal template

-          Conclusion: is it possible to formulate some perspectives, regarding the applicability of the method to other type of materials or historical buildings?

Author Response

Thank you very much for your comments and valuable suggestions on the article, which will help us to improve the article and we have revised the manuscript according to your suggestions. The specific responses are as follows:

1. We have changed the line space here and checked for other similar errors.
2. We have adjusted the width of table 4 and checked the formatting of the other charts.
3. We add to the applicability of the methodology and conclusions of this study.

Reviewer 2 Report (New Reviewer)

The article is an applied scientific work. The article presents quite clearly the results of the performed applied research.

The introduction provides a detailed overview of the research done by Chinese scientists for the red sandstones of China. In my opinion, it is of interest to compare similar investigations for sandstones in other countries.

The conclusion summarizes the results of the performed set of researches. But, in my opinion, there is also a general conclusion to be drawn. For example, predictions about the condition of red sandstone structures in the future, how the data obtained from the research can and should be used in the future, etc.

Author Response

Thank you very much for your comments and valuable suggestions that allowed us to identify the shortcomings of this article, which we have revised to the best of our ability based on your suggestions. The specific responses are as follows:

1. We have added a survey of research on sandstone in other countries in the introduction section, but in reviewing the literature, we found that Chinese scholars have carried out extensive and comprehensive research in this area, so we have not made any major changes to this section, and we hope that you will understand.
2. In the conclusion section, we add the value of the study's findings for use in real-world problems and the scope of their application.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Dear authors,

This is an interesting paper that can be improved. I attach here a file with several suggestions.

Best regards,

Comments for author File: Comments.pdf

Author Response

Thank you very much for your review suggestions, and we have made changes based on your suggestions. We have responded to your review comments line by line. Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The study was carried out on a single sample, which does not provide statistical parameters for the results.

Author Response

Thank you very much for your review comments, your suggestions are helpful, but unfortunately I did not receive a detailed list.
So I would like to answer directly some possible problems with the article, as the ancient buildings are more special and obtaining specimens back to cause damage to them, it is not possible to get more specimens. Therefore, in order to have reliable conclusions, we have tested and studied the data from several aspects.
The current study may have some shortcomings, and we will expand the direction and depth of the study and work on the application of practical problems in the next step.

Reviewer 3 Report

Monitoring of ancient structures is a difficult task worldwide. Appropriate restoration, protection or reinforcement strategies can then be based on the monitoring results, highlighting the need for precise and reliable monitoring methods.

The present manuscript exposes a study about the Characterization and degradation of ancient architectural red sandstone in a natural erosion environment. To this end several experimental techniques have been employed on a small red sandstone fragment: Scanning electron microscope (SEM), X-ray diffraction (XRD) 11 and X-ray computed tomography (X-CT). The results from the different techniques are analyzed separately and then compared and correlated to assess the degradation degree of the material. The manuscript is divided into four sections: an introduction with a good background about sandstone monitoring, a materials and methods section presenting part of the methods, a results section presenting the results, some methods and the correlation between the results, and a conclusion which summarizes the main research outputs.

Overall, this study may be of interest to the readers of the journal. though some clarifications and reorganizations are needed to ease the reading:

11.       L 47-97: this paragraph structure is not very clear. It is suggested to reorganize the sentences depending on the type of measurement, for example mechanical techniques, microscopy and other non destructive techniques

22.     L 69 ‘will make the sandstone.’ This sentence is not terminated properly

33.      L 71: please define SHPB

44.      L 79: maybe a new paragraph can be started after ‘in addition to this’

55.       L 83: define PFC3D model type

66.       L 127 briefly define GM(1,1) (model type, inputs)

77.      L 137-145: the detailed list of monuments is not needed (or maybe as a footnote)

88.     L 157: precise the height interval for h

99.     L 158-161: please revise the infinitive sentence

110.   Figure 1: indicate the exposed surface

111.   L 174: ‘wave value discounting’ is not specific enough. P-wave speed or a more precise denomination should be used

112.   L 175-177: the sentence about the works from the research team is not needed

113.   L 187: give RD brand rather than German-made comment

114.   L 192-197: revise the sentence

115.   L 200-207: positions of source and receiver should be clearly explained

116.   L 213: the voxel resolution is small for this sample size, is there any particular reason?

117.   Figure 3 is relatively redundant with Fig 2. At least an explanation about the color scheme should be added

118.   Figure 4: it is recommended to enlarge the figure (maybe splitting SEM and XRD figures in two separate figures)

119.   Figure 4: annotate SEM images with the identified species

220.   Figure 4: XRD spectra should be redrawn to decrease quartz peak height (using arbitrary units) so that the heights of the other peaks could be compared

221.   L 287: reference format is not adequate

222.   L 292-307: the reader might wonder why the authors did not compute directly porosity from the X-ray microCT images

223.   Eq 5: define Edx0. Does 0 stand for a time 0 or a reference layer?

224.   L 373: give greyscale values since it is difficult to read the graph

225.   Some paragraphs in section 3.3 belong to the Method section: line 437 to 465 and 484 to line 516

226.   Fig 9: why df is high than dfx and dfy? It is supposed to represent an average value.

227.   Eq 8: define x(0)(1), etc. Are there observables?

228.   L 591-594/ Maybe the reader would be interested by some degradations depths values

Author Response

Thank you very much for your review suggestions, and we have made changes based on your suggestions. We have responded to your review comments line by line. Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

No comments

Reviewer 2 Report

Thanks for corrections!

Reviewer 3 Report

The authors have addressed all the reviewers comments. The manuscript could be recommended for publication.